centaurea americana
centaurea melitensis

I see our database reflects ITIS and considers them "the same plant''

I was trying to add some data and find one /the yellow (melitensis) a invasive
and the other purple (americana) a native

I have trouble reconciling this

Help me understand how two so very different plants are the same?

Thanks

I was going to tell you that plants within a species can vary widely in their external characteristics (color, habit, etc.), and that taxonomic decisions are made on the basis of DNA analysis, so if the DNA's the same, so are the plants.

After doing some research on Centaurea americana, however, I've found something of a muddle.

Our database does not reflect ITIS, as you said, but the Catalogue of Life. Our information on the Centaurea genus is based on information in the CoL, which cites the June 2014 Global Compositae Checklist as the source of its classification of C. americana as a synonym of C. melitensis.

ITIS and GRIN, on the other hand, say that Centaurea americana is a synonym of Plectocephalus americanus, a name which is not listed in the Catalogue of Life.

The Plant List, as usual, turns things upside down and says that Plectocephalus americanus is a synonym of Centaurea americana. It cites the same source ITIS and GRIN used to declare the opposite, and it also brands Centaurea americana as an "unresolved" name.

The Catalogue of Life is the most recent source, but I wouldn't be surprised if there's some change in the taxonomic status of this name in the near future.

CoL claims 17-Sep-2013 for this entries latest taxonomic scrutiny. Which means that while GCC's last mention of it was in 2014, the last actual published work done on it was actually earlier than that.

Yes, but ITIS is 2010, GRIN is 2011, and The Plant List is 2012.

I notice that in the source given by CoL, the GCC, there are two listings for C. americana.

There's Centaurea americana Nutt. which is a synonym of Centaurea L.
and
Centaurea americana Spreng. which is a synonym of Centaurea melitensis but nom. illeg.

Nutt., Spreng., and L. are abbreviations of botanists' names (Nuttall, Sprengel, and Linnaeus). Nuttall first described C. americana in 1821. Sprengel then described it again in 1826. Sprengel's is listed as an illegitimate name (nom. illeg.) because the name was already published by Nuttall.

Thanks, zuzu, I understood they were authority names, but was confused as to why the synonym in the databases is with Sprengel's nom. illeg. and not Nuttall/Linnaeus? Also how a genus plus specific epithet can be a synonym of a genus-only name.

That part confused me also. I wonder whether Nuttall was simply relegating C. americana to the Centaurea genus named by Linnaeus instead of classifying it as a synonym. And how did Plectocephalus enter the picture for ITIS and GRIN? The whole thing seems muddled and incomplete.

zuzu said:... Sprengel then described it again in 1826. Sprengel's is listed as an illegitimate name (nom. illeg.) because the name was already published by Nuttall.

Thank you for the term "illegitimate name"!

It led me to all these very valuable terms of art. Now I have Latin names ... for Latin names!


https://en.wikipedia.org/wiki/...
"Nomen illegitimum (Latin for illegitimate name) is a technical term, used mainly in botany. It is usually abbreviated as nom. illeg."

(Unlike names written in Magic Marker on polyethylene plastic: nomina illegibilii.)

https://en.wikipedia.org/wiki/...

" ambiguous names, nomina ambigua, have been used with more than one meaning
names causing confusion, nomina confusa, are based on a mixed culture
perplexing names, nomina perplexa, confusingly similar names
perilous names, nomina periculosa, names that may lead to accidents endangering life or health or with potential serious economic consequences

In botanical nomenclature the phrase nomen dubium has no status, although it is informally used for names whose application has become confusing. In this regard however, its synonym nomen ambiguum is of more frequent use."

This naming confusion has appeared again on the Plant ID forum, The thread "Basket Flower (Centaurea melitensis)" in Plant ID forum

To recap what was said previously here and on that thread.
Centaurea melitensis L. validly published in 1753 (first publishing).
Centaurea americana Nutt. was validly published in 1821(first publishing).
Centaurea americana Spreng., was validly published in 1826 but is illegitimate because the name had already been validly published (second publishing).
Plectocephalus americanus (Nutt.) D. Don was validly published in 1830 (first publishing).

I've removed Centaurea americana Spreng. as a synonym of C. melitensis both because it is illegitimate and because it is confusing.
Therefor we have no entry in our database for the very different plant Centaurea americana Nutt./Plectocephalus americanus (Nutt.) D. Don.

The images by @Kelli in American Basket-Flower (Plectocephalus americanus) appear to be correct as noted by @HamiltonSquare and @JRsbugs. The other images appear to be of Centaurea americana Nutt.

While the correct name for Centaurea americana Nutt. is currently unresolved, the plant does exist and is referenced in many locations. Here are just a few of the links in Janet's posts.
http://www.wildflower.org/plan...
http://plants.usda.gov/core/pr...
http://sweetgum.nybg.org/vh/sp...

While we're always hesitant to add unresolved names to the database it appears that the best solution in this case is to do so.

Maltese Star Thistle (Centaurea melitensis)

I've added Plectocephalus americanus as a synonym and noted it's current nomenclature status as unresolved in a comment.

I can't understand how that yellow-blooming invasive and the wildflower species I've always know as Centaurea americana could ever be the same species.
The Wildflower Center doesn't show any yellow-blooming ones. Are you saying they're wrong?

LindaTX8 said:Are you saying they're wrong?

I think we're saying..."even they (the experts/taxonomists) don't actually know for sure at this moment".

Evan is trying to work 'a best possible' solution for the time being until they get it sorted out.

LindaTX8 said:The Wildflower Center doesn't show any yellow-blooming ones. Are you saying they're wrong?

They're correct. That's why I tree-mailed you asking to move your photos from American Basket-Flower (Plectocephalus americanus) to Maltese Star Thistle (Centaurea melitensis)

I finished editing the data fields and common names of both entries to limit the possibility of further confusion.